Buggy code:
public class AddVehicleUI { private JFrame frame ; private JTextField makeTxtField ; private JTextField modelTxtField ; private JTextField yearTxtField ; private JTextField colorTxtField ; private JTextField vinTxtField ; private JTextField mileageTxtField ; private JTextField optionsTxtField ; private JTextField mpgTxtField ; private JTextField priceTxtField ; private JTextField statusTxtField ; private JTextField purchaseDateTxtField ; private JTextField soldDateTxtField ; private JTextField qualityTxtField ; public AddVehicleUI ( ) { } private void initialize ( ) { frame = new JFrame ( ) ; frame . setBounds ( 100 , 100 , 464 , 700 ) ; <START_BUG> frame . setDefaultCloseOperation ( JFrame . EXIT_ON_CLOSE ) ; <END_BUG> frame . getContentPane ( ) . setLayout ( null ) ; JButton btnBack = new JButton ( "Back" ) ; btnBack . addActionListener ( new ActionListener ( ) { public void actionPerformed ( ActionEvent e ) { frame . dispose ( ) ; } } ) ; btnBack . setBounds ( 6 , 628 , 117 , 29 ) ; frame . getContentPane ( ) . add ( btnBack ) ; final JLabel lblMake = new JLabel ( "Make" ) ; lblMake . setBounds ( 28 , 19 , 43 , 39 ) ; frame . getContentPane ( ) . add ( lblMake ) ; final JLabel lblModel = new JLabel ( "Model" ) ; lblModel . setBounds ( 28 , 63 , 61 , 31 ) ; frame . getContentPane ( ) . add ( lblModel ) ; final JLabel lblYear = new JLabel ( "Year" ) ; lblYear . setBounds ( 28 , 99 , 36 , 39 ) ; frame . getContentPane ( ) . add ( lblYear ) ; final JLabel lblColor = new JLabel ( "Color" ) ; lblColor . setBounds ( 28 , 137 , 61 , 50 ) ; frame . getContentPane ( ) . add ( lblColor ) ; final JLabel lblVin = new JLabel ( "VIN" ) ; lblVin . setBounds ( 28 , 179 , 49 , 50 ) ; frame . getContentPane ( ) . add ( lblVin ) ; final JLabel lblMileage = new JLabel ( "Mileage" ) ; lblMileage . setBounds ( 28 , 220 , 49 , 50 ) ; frame . getContentPane ( ) . add ( lblMileage ) ; final JLabel lblOptions = new JLabel ( "Options" ) ; lblOptions . setBounds ( 28 , 267 , 61 , 50 ) ; frame . getContentPane ( ) . add ( lblOptions ) ; final JLabel lblMpg = new JLabel ( "MPG" ) ; lblMpg . setBounds ( 28 , 347 , 61 , 50 ) ; frame . getContentPane ( ) . add ( lblMpg ) ; final JLabel lblPrice = new JLabel ( "Price" ) ; lblPrice . setBounds ( 28 , 406 , 43 , 29 ) ; frame . getContentPane ( ) . add ( lblPrice ) ; final JLabel lblStatus = new JLabel ( "Status" ) ; lblStatus . setBounds ( 28 , 435 , 49 , 50 ) ; frame . getContentPane ( ) . add ( lblStatus ) ; final JLabel lblPurchasedDate = new JLabel ( "Purchased<seq2seq4repair_space>Date" ) ; lblPurchasedDate . setBounds ( 28 , 475 , 104 , 50 ) ; frame . getContentPane ( ) . add ( lblPurchasedDate ) ; final JLabel lblSoldDate = new JLabel ( "Sold<seq2seq4repair_space>Date" ) ; lblSoldDate . setBounds ( 28 , 515 , 61 , 50 ) ; frame . getContentPane ( ) . add ( lblSoldDate ) ; makeTxtField = new JTextField ( ) ; makeTxtField . setBounds ( 131 , 24 , 200 , 29 ) ; frame . getContentPane ( ) . add ( makeTxtField ) ; makeTxtField . setColumns ( 10 ) ; modelTxtField = new JTextField ( ) ; modelTxtField . setColumns ( 10 ) ; modelTxtField . setBounds ( 131 , 64 , 200 , 29 ) ; frame . getContentPane ( ) . add ( modelTxtField ) ; yearTxtField = new JTextField ( ) ; yearTxtField . setColumns ( 10 ) ; yearTxtField . setBounds ( 131 , 104 , 200 , 29 ) ; frame . getContentPane ( ) . add ( yearTxtField ) ; colorTxtField = new JTextField ( ) ; colorTxtField . setColumns ( 10 ) ; colorTxtField . setBounds ( 131 , 148 , 200 , 29 ) ; frame . getContentPane ( ) . add ( colorTxtField ) ; vinTxtField = new JTextField ( ) ; vinTxtField . setColumns ( 10 ) ; vinTxtField . setBounds ( 131 , 190 , 200 , 29 ) ; frame . getContentPane ( ) . add ( vinTxtField ) ; mileageTxtField = new JTextField ( ) ; mileageTxtField . setColumns ( 10 ) ; mileageTxtField . setBounds ( 131 , 231 , 200 , 29 ) ; frame . getContentPane ( ) . add ( mileageTxtField ) ; optionsTxtField = new JTextField ( ) ; optionsTxtField . setColumns ( 10 ) ; optionsTxtField . setBounds ( 131 , 278 , 200 , 29 ) ; frame . getContentPane ( ) . add ( optionsTxtField ) ; mpgTxtField = new JTextField ( ) ; mpgTxtField . setColumns ( 10 ) ; mpgTxtField . setBounds ( 131 , 358 , 200 , 29 ) ; frame . getContentPane ( ) . add ( mpgTxtField ) ; priceTxtField = new JTextField ( ) ; priceTxtField . setColumns ( 10 ) ; priceTxtField . setBounds ( 131 , 406 , 200 , 29 ) ; frame . getContentPane ( ) . add ( priceTxtField ) ; statusTxtField = new JTextField ( ) ; statusTxtField . setColumns ( 10 ) ; statusTxtField . setBounds ( 131 , 446 , 200 , 29 ) ; frame . getContentPane ( ) . add ( statusTxtField ) ; purchaseDateTxtField = new JTextField ( ) ; purchaseDateTxtField . setColumns ( 10 ) ; purchaseDateTxtField . setBounds ( 131 , 486 , 200 , 29 ) ; frame . getContentPane ( ) . add ( purchaseDateTxtField ) ;

Fix:
frame . setDefaultCloseOperation ( frame . DISPOSE_ON_CLOSE ) ;